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Commit ec99f6d3 authored by Elena Reshetova's avatar Elena Reshetova Committed by Miklos Szeredi
Browse files

fuse: convert fuse_req.count from atomic_t to refcount_t 



refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: default avatarElena Reshetova <elena.reshetova@intel.com>
Signed-off-by: default avatarHans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarDavid Windsor <dwindsor@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 4e8c2eb5

fs/fuse/dev.c

+4 −5
Original line number Diff line number Diff line
@@ -45,7 +45,7 @@ static void fuse_request_init(struct fuse_req *req, struct page **pages, 
	INIT_LIST_HEAD(&req->list);

	INIT_LIST_HEAD(&req->intr_entry);

	init_waitqueue_head(&req->waitq);

	atomic_set(&req->count, 1);

	refcount_set(&req->count, 1);

	req->pages = pages;

	req->page_descs = page_descs;

	req->max_pages = npages;
@@ -102,14 +102,13 @@ void fuse_request_free(struct fuse_req *req) 


void __fuse_get_request(struct fuse_req *req)

{

	atomic_inc(&req->count);

	refcount_inc(&req->count);

}



/* Must be called with > 1 refcount */

static void __fuse_put_request(struct fuse_req *req)

{

	BUG_ON(atomic_read(&req->count) < 2);

	atomic_dec(&req->count);

	refcount_dec(&req->count);

}



static void fuse_req_init_context(struct fuse_req *req)
@@ -264,7 +263,7 @@ struct fuse_req *fuse_get_req_nofail_nopages(struct fuse_conn *fc, 


void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)

{

	if (atomic_dec_and_test(&req->count)) {

	if (refcount_dec_and_test(&req->count)) {

		if (test_bit(FR_BACKGROUND, &req->flags)) {

			/*

			 * We get here in the unlikely case that a background

fs/fuse/fuse_i.h

+1 −1
Original line number Diff line number Diff line
@@ -307,7 +307,7 @@ struct fuse_req { 
	struct list_head intr_entry;



	/** refcount */

	atomic_t count;

	refcount_t count;



	/** Unique ID for the interrupt request */

	u64 intr_unique;